How may I add support to avoid this artifact?  

How may I add support to avoid this artifact?

I have tried several approaches to removing a flaw in a print and I have failed. I ask for your assistance in allowing me to fix this flaw.

I have attached STL, 3MF, and G-code files (ZIP’d) so that you can see what I did. These files represent, just a portiont of a larger part from which the example files were removed for this print. I printed this part, and it does exhibit the flaw.

I printed this on a factory-assembled CORE One with current firmware and with the current Prusa Slicer in Overture PETG. While printing, I can see that the problem is Y-axis vibration as the print head gets further from the base. The problem stops when printing bridges the top of the “window” thereby connecting and stabilizing the panel.

I believe that what I need to do is to provide a support resisting Y-axis motion on the unsupported panel in the problem area. It seems like that type of support is not available in the slicer. Additionally, this part, in production will have a fuzzy skin, and it seems that the current slicer does not allow for both supports and fuzzy skin.

To work around my lack of knowledge regarding support options, I jury-rigged a “plug” in the “window” with spaced projection-points on sides, top, and bottom of the “window” to stabilize the otherwise unsupported panel. With trial and error, I found that a 0.003-inch clearance provided a plug that did stabilize and was removable, yet it left unacceptable residuals on the window edges.

I have likely overlooked some built-in solution or easy workaround. Will you please help me out and educate me?